ADCP in the Ottawa River Flood Management

1. Where is the Ottawa River?

The Ottawa River is a significant river in Canada. It lies in the eastern part of the country and forms the borderline between Ontario and Quebec.

It is geographically issuing from the Laurentian Highlands in western Quebec. The river has almost all types of landscapes: forests, hills, and plains. Coming to its course, it deals with many cities and towns such as but not limited to Ottawa - that is, the capital city of Canada, Gatineau, and Pembroke. It serves as a vital transportation route and as a great water source for many needs like hydro-electricity generation, domestic water supply, and even recreation activities.

The region containing the Ottawa River experiences a humid continental climate in terms of precipitation. Through the year, rainfall is scattered; however, spring and summer periods are somewhat wetter due to convective thunderstorms and frontal systems. Spring also contributes a great deal to the water volume in the river through snowmelt. These fluctuations can lead to the extreme behavior of water levels when a lot of rainfall falls within a short period or snowmelt happens very fast. This leads to flooding.

2. Why does Ottawa River flood?

Heavy Rainfall: High-intensity, sustained rainfall over the catchment area of the river is the main cause. Thunderstorms during the summer may have heavy rains falling in a very short period of time. The infiltration capacity of the soil may be surpassed; a large quantity of the rainwater flows into the river, thereby increasing the water level abruptly.

Snowmelt: Snowpack that builds up throughout the winter may melt during the spring and create flooding. If the temperatures rise too quickly, the snowmelt can be rapid. At times, when this happens, a river cannot support the sudden surge of water from snowmelt if it is combined with heavy rainfall.

Topography: Topography is the shape and features of the river basin area. There are low-lying areas, floodplains along the river where water tends to accumulate. The presence of flat areas slows down the flow of water, which can accumulate and flood.

Human Activities: Among the human activities that have imparted impacts on it are urban development and agriculture. Thus, building structures and other constructions like roads on a floodplain area reduces the natural flood-carrying capacity of the river. Agricultural activities, on one hand, enhance drainage of lands, compact the soil, which in turn enhances surface runoff and sedimentation. The deposited sediments reduce the effective cross-sectional area of the river and make it susceptible to flooding.

ADCP current meter stands for Acoustic Doppler Current Profiler; it involves a more developed and friendly approach in the measurement and control of the flow conditions of the river, especially during flood events.

3. How do ADCPs using the principle of Doppler work?

The Acoustic Doppler Current Profiler(ADCP) work on the principle of the Doppler. The ADCP flow meter sends out an acoustic signal into the water; this signal interacts with moving particles of water. Due to the water in motion, the frequency of the reflected acoustic signal will shift due to the Doppler effect.

ADCP measures the difference in frequency between the emitted and the received acoustic signal. With that frequency shift, it can calculate the velocity of the water at various different depths. It generally has many transducers that could send and receive acoustic signals in various different directions, allowing a profile of water velocity across a section of the river.

For example, if the water is flowing towards the ADCP current profiler, it will have a higher frequency than that emitted; and vice versa, if the water is flowing away. These frequency changes are measured to extreme precision in order to calculate, by appropriate mathematical algorithms, the velocity of water at various points within its measurement range.

4. The applications of the ADCP in floods of the Ottawa River.

Velocity Measurement: The ADCP becomes very important during floods for making precise measurements in the water flow velocity. This will continuously monitor the water velocity at different depths and locations, giving real-time data on the water's speed of movement. This comes in handy in the understanding of the dynamics of a flood; therefore, it avails necessary information on the direction and intensity of movement of the floodwaters.

Flow Measurement: ADCP meter can also calculate flow rates of the Ottawa River by measuring water velocities at several points across the section of a river and using well-known cross-sectional area of the river to calculate the total volume of water that flows through this section per unit time, giving the flow rate. This information is fundamental in calculating the total amount of water in a flood and thus creates a basis on which decisions on flood control and water resource management are founded.

Usefulness in Sediment Transport Research: Other than measuring flow and velocity, ADCP profiler will be useful in sediment transport research along the Ottawa River during floods. While water is in motion, it carries sediments with it; an ADCP measures changes in the backscattered acoustic signal generated by the presence of sediments. From such changes, researchers can estimate the quantity and movements of sediments-a crucial knowledge about the long-term evolution of the riverbed and the action of floods on the river's sedimentary environment.

5. How can the data measured by ADCP be used in flood warning and risk management of the Ottawa River?

Flood Warning:

Velocity and Flow Data Monitoring: Real-time flow velocity and magnitude data acquired by ADCP are monitored continuously. This gives information about the upcoming flood peak or a plausible flood situation if the measured water velocity is higher than the given threshold value or in other cases where there is a considerable increase in the flow rate. This will give ample warning to the relevant authorities for precautions to be taken, such as the evacuation of people in low-lying areas or strengthening flood defenses.

Water Level Prediction and Warning: It can predict the future water level by correlating the measured flow data with historical data of the water level, using appropriate hydrological models. If it is found that the predicted water level is going to be higher than that of the flood warning level, timely warnings can be issued to enable the public to prepare for the flood.

Risk Management:

Water Conservancy Project Scheduling Decision Support: Flow data and velocity information measured by ADCP can facilitate decisions regarding the operation of water conservancy projects, such as operations related to dams and sluices. For example, with the measured water flow, one may adjust the amount of water released from a dam to control the level of water in the Ottawa River so as to minimize the effect of flooding.

Flood Disaster Assessment and Emergency Response: The ADCP data can subsequently be analyzed to determine the damage caused by a flood, the depth of the inundation, the velocities of the resultant floodwaters, and the sediment carried by these waters. This information is very useful in formulating emergency response plans and in carrying out post-flood reconstruction and rehabilitation work.

6. What does high quality measurement of the current of the Ottawa River demand?

• Reliable Material of Equipment: The equipment used, especially the casing of the ADCP, should be made with reliable material to ensure a high-quality measurement. Titanium alloy is an example. It has high strength for allowing the equipment to resist the pressure and impact exerted by the water flow. It is also highly resistant to corrosion, which would be very important given that the Ottawa River's water environment might contain several corrosive materials.
• Adequate Size and Weight: The size and weight of the equipment should be compact and lightweight. This makes it easy to install and operate the ADCP in various locations along the river, particularly those that are difficult to access.
• Low Power Consumption: The power consumption should be low in order to allow longer continuous operations without frequent changes of batteries or connection to a power source.
• Cost-effectiveness: Should have a relatively low capital cost for wide measurements to be possible. The lower the cost, the more acoustic doppler velocity meter can be used across the Ottawa River in providing larger and more detailed information for flood management.

7. How to Choose right equipment for current measurement?

• Type of Measurement: The selection would depend upon the kind of measurement one intends to make, be it for horizontal cross-section measurement or the other. Here, in the case of the former requirement, the user must opt for Horizontal ADCP and, in the case of the latter, for Vertical ADCP.
• Water Depth to Be Considered: Different frequencies are suitable for different water depths. For example, an ADCP operating at 600 kHz is intended for water depths within a limit of 70 m. If the water depth in the Ottawa River falls within this range and the measurement requirements are as shown here, then a 600 kHz ADCP will be a consideration. For deeper waters, over 70 m up to 110 m, an ADCP of 300 kHz will be more appropriate since it may carry out more accurate measurements in such depths. There are quite a few popular brands known in the ADCP market. Teledyne RDI, Nortek, and Sontek will be named here.

But for those thrifters, one of the best deals might be the China Sonar ​PandaADCP. It is all made out of titanium alloy material, surely not compromising its quality and dependability in the water environment. Moreover, it offers an extremely remarkable cost-to-performance ratio. You can find more information on its official website at: (​https://china-sonar.com/).

Here is a table with some well known ADCP instrument brands and models.